Absorbent articles, such as diapers or incontinence guards, are articles which are worn adjacent the body, and used for the containment and absorption of bodily exudates, such as urine, blood, faeces and sweat. Such articles are usually supplied with elastic members (commonly in the form of one or more elastic threads). In the interests of manufacturing efficiency and economy, the elastic members are located in selected regions of the article, such as leg openings, waist openings, standing gathers etc. Elastic members have a number of functions—they inter alia help to maintain the article in place on the wearer, they provide the article with a suitable three-dimensional form and they help to seal portions of the article against the skin of the wearer, thus reducing the risk of leakage.
Absorbent articles are manufactured in high volumes, at high speeds. Methods are therefore required which allow the incorporation of elastic members (e.g. in the form of one or more elastic threads) into or onto other components of an absorbent article during manufacture. Elastic members are usually only located in regions of the absorbent article, but are often supplied in continuous form (e.g. on a roll), so one or more steps of cutting the elastic members is usually required. This in turn leads to difficulties in maintaining the correct tension in the elastic members, and may cause crumpling, foreshortening or wrinkling of the elasticated components.
A particular issue is found with elastic members located in the crotch portion of absorbent articles—i.e. that portion which is located between the wearer's legs when the article is worn. It is generally undesirable that elastic members are located in the crotch portion, as they can cause chafing/rubbing in this sensitive area. In addition, elastic members which are arranged across an absorbent core can cause the core to deform. This in turn causes problems in terms of appearance (due to bunching) and liquid handling (due to undesired compression of the absorbent core causing liquid-channelling creases).
U.S. Pat. Nos. 5,660,657 and 5,643,396 disclose methods for constructing garments including stretched elastic. U.S. Pat. No. 4,379,016 describes a method and device for applying elastic strips in sections onto a web of material. U.S. Pat. No. 6,179,946 describes a process for making a composite sheet. U.S. Pat. Nos. 6,482,278 and 6,521,320 disclose pant-type diapers, and methods for their manufacture. WO 97/00654 discloses an apparatus and a method for applying elastic thread to a web.